2010-24745. Airworthiness Directives; Rolls-Royce plc RB211-Trent 800 Series Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

This supplemental NPRM revises an earlier proposed airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

During manufacture of high-pressure (HP) compressor stage 1 discs, a small number of parts have been rejected due to a machining defect that was found during inspection. Analysis of the possibility of less severe examples having been undetected and passed into service has concluded that action is required to reduce the risk of failure. It was therefore necessary to reduce the life limit.

The HP compressor stage 1 disc is part of the HP compressor stage 1-4 shaft, part number (P/N) FK32580. We are proposing this AD to prevent failure of the HP compressor stage 1 disc, uncontained engine failure, and damage to the airplane.

DATES:

We must receive comments on this proposed AD by November 18, 2010.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12-140, Washington, DC 20590-0001.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
• Fax: [phone].

Contact Rolls-Royce plc, P.O. Box 31, Derby, England, DE248BJ; telephone: [phone]; fax: [phone] for the service information identified in this proposed AD.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (phone [phone]) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2008-1165; Directorate Identifier 2008-NE-38-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD based on those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of the Web site, anyone can find and read the comments in any of our dockets, including, if provided, the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78).

Discussion

This supplemental NPRM revises an earlier proposed AD, for Rolls-Royce plc RB211-Trent 800 series turbofan engines. That proposed AD would have required removing HP compressor stage 1-4 shafts, P/N FK32580, from service at reduced life limits based on part assessment using either “Multiple Flight Profile Monitoring”, or “Heavy Flight Profile” calculations. That proposed AD resulted from MCAI issued by an aviation authority of another country. This supplemental NPRM revises the proposed AD to correct certain life limits for the Heavy Flight Profile Parts. We are proposing this supplemental NPRM to prevent failure of the HP compressor stage 1 disc, uncontained engine failure, and damage to the airplane. The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued MCAI AD 2010-0087, date May 5, 2010 (corrected, May 6, 2010), to correct an unsafe condition for the specified products. The MCAI states:

During manufacture of high-pressure (HP) compressor stage 1 discs, a small number of parts have been rejected due to a machining defect that was found during inspection. Analysis of the possibility of less severe examples having been undetected and passed into service has concluded that action is required to reduce the risk of failure. It is therefore necessary to reduce the life limit.

Since we issued the original proposed AD on February 10, 2009 (74 FR 7563, February 18, 2009):

• EASA issued AD 2010-0087, dated May 5, 2010, and AD 2010-0087 (corrected May 6, 2010) to correct certain life limits for the Heavy Flight Profile Parts.
• EASA issued AD 2010-0087, dated May 5, 2010 (corrected May 6, 2010), which retains certain requirements of superseded EASA AD 2008-0099, and imposes more restrictive life limits in the Heavy Flight Profile Parts.

You may obtain further information by examining the MCAI in the AD docket.

Comments

We provided the public the opportunity to participate in the development of the original proposed AD. We considered the comments received.

NPRM Would Allow a Part To Go Beyond the Current Time Limits Manual (TLM) Limit

One commenter, Delta Airlines through the Airline Transport Association (ATA), states that the NPRM would require a 5,280 cycle life limit established in the long term for shafts that are used in the “Heavy Flight Profile”. In the draw down period from the initial effective date, the NPRM would allow a shaft in the “Heavy Flight Profile” category to remain in service for up to 7,480 flight cycles in the worst case scenario. However, the existing TLM Section 05-10-01-800-802, Subtask 05-10-01-860-169 (dated March 15, 2008) states that the current declared life limit for HP compressor stage 1-4 shaft, P/N FK32580, is only 6,850 flight cycles. The NPRM would allow a part to go beyond the current TLM limit in the interim draw down period which seems to contradict the intent of the NPRM.

We agree. We changed the supplemental NPRM to use the correct life limit reduction.

Allow Later Approved Revisions of the Alert Service Bulletin (ASB) as Acceptable for Compliance

One commenter, American Airlines through the ATA, states that subsequent to the writing of the NPRM, Rolls-Royce plc published Revision 2 of ASB No. RB.211-72-AF825. The commenter requests that the AD should include language that allows later approved revisions of the ASB as acceptable for compliance.

We partially agree. We agree that our ADs should be as current and accurate as possible. We changed the AD to include the reference to ASB Revision 3 in the related information paragraph.

We disagree that the NPRM, or this supplemental NPRM, require the use of the ASB for compliance, or that we should permit an unknown future revision be used for compliance. Since we do not know the content of later documents like ASBs, we do not issue a regulation that mandates compliance with the unknown. We did not change the proposed AD to permit compliance to unknown future revisions.

Request To Change the Base-Lined Compliance Time in the AD

One commenter, Rolls-Royce plc, states that their SB compliance time is base-lined from May 1, 2008. The FAA NPRM is understood to permit the same cyclic draw down as the SB. However, the baseline date for the applicable draw down would be the issue date of the FAA AD. Rolls-Royce plc requests that we change the base-lined compliance time in the proposed AD to the compliance base line in the RR SB.

We do not agree. We cannot pre-date the compliance times in the proposed AD. We did not change the AD.

Differences Between This Proposed AD and the MCAI

We have reviewed the MCAI and, in general, agree with its substance. But we have found it necessary to not incorporate the June 4, 2008 compliance date which is in EASA AD 2010-0087, dated May 5, 2010 (corrected May 6, 2010). We updated the compliance times in the proposed AD based on a more recent assessment of the unsafe condition.

FAA's Determination and Requirements of This Proposed AD

This product has been approved by the aviation authority of the United Kingdom, and is approved for operation in the United States. Pursuant to our bilateral agreement with the United Kingdom, they have notified us of the unsafe condition described in the MCAI and service information referenced above. We are proposing this AD because we evaluated all information provided by EASA and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design. This proposed AD requires removing HP compressor stage 1-4 shafts, P/N FK32580, from service at reduced life limits based on part assessment using either “Multiple Flight Profile Monitoring”, or “Heavy Flight Profile” calculations.

Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 78 products of U.S. registry. Required parts would cost about $15,095 per product. We estimate that no additional labor costs would be incurred to perform the proposed actions, as we anticipate that the removal from service of the HP compressor stage 1-4 shafts will occur while the engine is inducted into the shop for routine maintenance. Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $1,177,410.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify this proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

Rolls-Royce plc: Docket No. FAA-2008-1165; Directorate Identifier 2008-NE-38-AD.

Comments Due Date

(a) We must receive comments by November 18, 2010.

Affected Airworthiness Directives (ADs)

(b) None.

Applicability

(c) This AD applies to Rolls-Royce plc (RR) models RB211-Trent 875-17, -Trent 877-17, -Trent 884-17, -Trent 884B-17, -Trent 892-17, -Trent 892B-17, and -Trent 895-17 turbofan engines, with high-pressure (HP) compressor stage 1-4 shafts, part number (P/N) FK32580, installed. These engines are installed on, but not limited to, Boeing 777 series airplanes.

Reason

(d) European Aviation Safety Agency (EASA) AD 2010-0087, dated May 5, 2010 (corrected May 6, 2010) states the unsafe condition is as follows:

During manufacture of high-pressure (HP) compressor stage 1 discs, a small number of parts have been rejected due to a machining defect that was found during inspection. Analysis of the possibility of less severe examples having been undetected and passed into service has concluded that action is required to reduce the risk of failure. It was therefore necessary to reduce the life limit.

The HP compressor stage 1 disc is part of the HP compressor stage 1-4 shaft, P/N FK32580. We are issuing this AD to prevent failure of the HP compressor stage 1 disc, uncontained engine failure, and damage to the airplane.

Actions and Compliance

(e) Unless already done, do the following actions.

Multiple Flight Profile Monitoring Parts

(1) For RB211-Trent 800 engines being monitored by “Multiple Flight Profile Monitoring,” remove the HP compressor stage 1-4 shaft, P/N FK32580, before accumulating 5,580 standard duty cycles (SDC) since-new or within 960 SDC from the effective date of this AD, whichever occurs later.

Heavy Flight Profile Parts

(2) For RB211-Trent 800 engines being monitored by “Heavy Flight Profile,” remove the HP compressor stage 1-4 shaft, P/N FK32580, before accumulating 5,280 flight cycles since new or within 860 flight cycles from the effective data of this AD, whichever occurs later.

FAA Differences

(f) We have found it necessary to not incorporate the June 4, 2008 compliance date which is in EASA AD 2010-0087, dated May 5, 2010 (corrected May 6, 2010). We also updated the compliance times in the AD based on a more recent assessment of the unsafe condition.

Alternative Methods of Compliance (AMOCs)

(g) The Manager, Engine Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

Related Information

(h) Refer to EASA Airworthiness Directive 2010-0087, dated May 5, 2010 (corrected May 6, 2010), and Rolls-Royce plc Alert Service Bulletin No. RB.211-72-AF825, Revision 3, dated August 25, 2009 for related information. Contact Rolls-Royce plc, P.O. Box 31, Derby, England, DE248BJ; telephone: [phone]; fax: [phone], for a copy of this service information.

(i) Contact James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: [e-mail]; telephone [phone]; fax [phone], for more information about this AD.

Issued in Burlington, Massachusetts on September 27, 2010.

Peter A. White,

Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service.